Quantum Number Problems  Problems

Electron Configuration and Quantum Number Problems

1)  What are the four quantum numbers and what do they indicate?

n is the principal quantum number and is the energy level
n describes the relative electron cloud size

l is the sublevel; it describes the shape of the electron cloud

m, is the orbital; it describes the orientation in space of each orbital

s is the direction of the spin of the electron

2)  If an element possesses n = 3, what are the possible l values?
What are the possible m values?

if n = 3, then there are 3 sublevels
the sublevels would be s=1, p=2, and d=3
m would be the orbitals
s has one orbital; 0
p has 3 orbitals; -1, 0 1
d has 5 orbitals;  -2, -1, 0, 1, 2   these would be the possible m values

3a)  Write out the electron configuration for Na, S, Mo, Ne, and Ce. (The whole thing!!!)
3b)  Draw the Lewis dot diagram.
3c)  How many valence electrons does each of those elements have?
3d)  What is the oxidation number for each of those elements?
3e)  What are the quantum numbers for each of those elements?

 -3 -2 -1 0 1 2 3

Na  1s2 2s2 2p6 3s1      Na .      1 valence electron    +1 oxidation number
3s1        n=3    L = 1   m = 0  s = +1/2

..
S   1s2 2s2 2p6 3s2 3p4   ..  S. .     6 valence electrons   -2 oxidation number
3p4        n=3    L = 2   m = -1  s = -1/2

Mo 1s2 2s2 2p6 3s2 3p64s2 3d10 4p6 5s2 4d4     Mo. .
2 valence electrons    +2  oxidation number, transition metal
others possible:
4d4        n=4    L = 3   m = 1  s = +1/2

..
Ne  1s2 2s2 2p6          .. Ne ..      8 valence electron    no oxidation number  8 is great!
..

2p 6       n=2    L = 2   m = 1  s = -1/2

Ce 1s2 2s2 2p6 3s2 3p64s2 3d10 4p6 5s2 4d10 5p6 6s2 4f2
Ce. .     2 valence electrons   +2 oxidation number
lanthanoid metal, others possible
4f2        n=4    L = 4   m = -2  s = +1/2

4)  What is the charge of noble gases? Why? Where do I find noble gases on the periodic table?

have no charge, not usually ions,  have 8 valence electrons and are considered stable
group 18 (VIII) far right column on periodic table
He, Ne, Ar, Kr, Xe, and Rn

5)  What is the charge of halogens? Why? Where do I find them on the periodic table?

when halogens form ions, they want to gain one electron, so their charge is -1
the are on the right hand side of the periodic table next to the noble gases group VII
F, Cl, Br, I, At

6)  What is the charge of alkaline earth metals? Why?
Where do I find them on the periodic table?

alkaline earth metals have 2 valence electrons so their oxidation number is +2
they are the second column from the left, group II
Be, Mg, Ca, Sr, Ba, Ra

7)  Why are transition metals in transition? Why do you want a list of their charges for the test?

They have a d sublevel which has less energy than the s level, consequently all transition
metals have 2 valence electrons.
The d sublevel electrons may prevent the atom from spinning smoothly, the atom may lose
more than 2 electrons if it will help balance the atom.

8) Where are the metalloids?

metalloids are found to either side of the zigzag line or the staircase line
they include B, Al, Si, Ge, As, Sb, Te, Pl, and At

Quantum Number Problems